The proposed urban goal is both interesting and important because — given that implementation of globally agreed targets is ultimately local — it is the only goal that is location-specific at a manageable scale. This is significant in that a city represents a microcosm of all the other goals.

In this context, if we can get urban areas on the right path to sustainable development, we stand a good chance of positively influencing progress on virtually all the other goals. Currently, just over half of the world’s population is classified as living in urban areas, a proportion that is predicted to rise to 66% by the middle of this century – representing an additional 2.5 billion people

While megacities (urban areas with more than 10 million inhabitants) are set to increase in number, most urban residents live in smaller secondary cities, This is where most of the growth is set to come. The implication of this is that much city building is yet to take place (one estimate, for example, asserts that “70 to 80 percent of the India of 2030 is yet to be built”). Given the decadal lifespans of many pieces of urban infrastructure, this presents a once-in-a-lifetime opportunity to get things right in the planning of cities, in order to establish the foundation for sustainable urban futures.

It is often noted that in an urbanised world, cities are both the source and solution of many global problems. For although cities are efficient users of land, they have footprints that extend far beyond the city limits.

The Sustainable Development Goals still seem rather siloed. But as other commentators in this series have pointed out, even within a specific goal there is often much that is missed. Cities, however, are exceptional areas through which to understand new ways of linking multiple development goals. Due to their density, urban areas are great places to identify systematic linkages between economy, energy, environment, and social outcomes at close quarters and, in turn, to find the synergies (and trade-offs) that can lead to coherent and mutually reinforcing policies on urban development.

Take the urban transport target of SDG #11 as an example: it simultaneously facilitates the production of air pollution (and, by association, health outcomes) as well as economic activity through the efficient movement of workers and increased social intercourse through the city. Effective public transport systems enable compact cities that would limit land consumption (another target of goal #11) while imaginative urban design and provision of green space could positively influence biodiversity in cities and elements of human health and well-being.

In this regard, the co-benefits approach can be useful to help understand what are the links and synergies in the urban system between many of the targets within the various goals, but also between goals themselves. UNU-IAS has developed tools in different sectors that can quickly show the impacts of different policies and local- and global-emissions of pollution.

The potential of cities, however, goes far beyond what is contained in SDG #11. Because cities are massive producers of waste, energy generation becomes a possibility as well as the use of urban infrastructure for local energy generation. Much of the agenda on sustainable consumption and production (goal #12) will be determined by urban consumption patterns, which also link to the consumption of marine and rare (trafficked) species.

To enable this vision, two areas need attention.

First, we need to systematically collect and share all kinds of urban data to understand how key indicators on the city are responding. Despite the seeming availability of data, in practice the distributed nature, collection, and organisation, of even fundamental city datasets have proven to be obstacles in understanding the scale of the problem. As automation of many urban services increases, however, we will see a massive augmentation of large arrays of data (big data) as well as data being generated through social networks.

Second, we need to improve urban governance. We must acknowledge the inherent complexities of urban activities, and create virtuous (as opposed to vicious) cycles of urban governance, whereby solutions would alter patterns of urban development, which in turn could reduce vulnerability and environmental impacts.

One component of this vision would be a systems thinking approach that can help understand where dominant feedbacks occur in the urban system, and communicate this to diverse stakeholders. Such a process requires the use of inter- and trans-disciplinary knowledge to help understand and aid the effective design and roll-out of sustainable development policies.

Enlightened urban governance — that recognises the linkages existing within cities, and also their impact on the wider world (including the use of resources and impact on biodiversity in far-off places) — would be a shot in the arm in achieving many of the SDGs. As cities are also home to most (if not all) decision-makers, cities will play a central organising role in achieving wider sustainable development.